Redundant control system for lcd

ABSTRACT

In an exemplary embodiment, each horizontal and vertical conductor of a TFT array may be in electrical contact with a first and second control system. Initially, the entire display is driven by the first control system. When/if a failure occurs in the first control system, it is powered down and the second control system maintains operation of the entire display. Each control system may contain a set of source/gate drivers, display interface board, and power supply. A reversionary button may allow the user to manually switch between control systems. Alternatively, failure may be detected by the display interface boards or a graphics processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to co-pending U.S. Application Nos.61/583,275 filed on Jan. 5, 2012, 61/657,463 filed on Jun. 8, 2012, and61/711,804 filed on Oct. 10, 2012; each application is hereinincorporated by reference in its entirety.

TECHNICAL FIELD

Disclosed embodiments relate generally to a redundant interwoven TFTarray for a liquid crystal display device.

BACKGROUND OF THE ART

LCDs are becoming popular for not only home entertainment purposes, butare now being used as informational/advertising displays in both indoorand outdoor locations as well as within moving vehicles subject tosubstantial shock. When used for information/advertising purposes, thedisplays may remain ‘on’ for extended periods of time and thus would seemuch more use than a traditional home theatre use. When used forextended periods of time and placed within vehicles subject to shock,durability of the components can become an issue.

Liquid Crystal Displays (LCDs) contain several layers which work incombination to create a viewable image. A backlight is used to generatethe rays of light that pass through what is commonly referred to as theLCD stack, which typically contains several layers that perform eitherbasic or enhanced functions. The most fundamental layer within the LCDstack is the liquid crystal material, which may be actively configuredin response to an applied voltage/charge in order to pass or block acertain amount of light which is originating from the backlight. Thelayer of liquid crystal material is divided into many small regionswhich are typically referred to as pixels. For full-color displays thesepixels (color groups) are typically divided intoindependently-controllable regions of red, green and blue subpixels,where the red subpixel has a red color filter, blue subpixel has a bluecolor filter, and green subpixel has a green color filter. Each subpixelmay be controlled by a grid of intersecting conductors which can apply aspecific voltage to each subpixel to create an image.

An LCD will not function satisfactorily without an appropriate andproperly-functioning set of source and gate drivers and associatedconductor lines. If a conductor were to fail, then the entire column orrow of the LCD may cease operations. Further, if either the gate driver,source driver, or the power supply to either of these drivers were tofail, the entire LCD may fail to create an image. While this may be asimple inconvenience when LCDs are used for entertainment purposes, whenused for information or data displays this can be very costly. Forexample, LCDs are now being used in aircraft cockpits as well as theinstrument panels or display(s) in ground vehicles and marine equipment.In these applications, when there is a failure within the controlsystem, the LCD may no longer display the important information for thevehicle/aircraft and controls may cease to operate. These situations canbe undesirable not only to the passengers of the vehicle/aircraft, butalso other soldiers/team members who are counting on this part of themission.

Some control systems have a limited life span, and eventually theirperformance may suffer. Some systems may quickly fail simply due to amanufacturing defect or may fail due to shock/forces applied to theaircraft or ground vehicle. Currently when this occurs, the entire LCDdevice must be manually replaced. This is expensive, and is often timeconsuming. Alternatively, the LCD device could be removed from thedisplay housing, and the degraded or faulty system elements could bemanually replaced. This is typically even more costly, and involvesextensive manual labor. In currently known units, this also requiresvirtual complete disassembly of the LCD to gain access to theelectronics. This complete disassembly is not only labor intensive, butmust be performed in a clean room environment and involves the handlingof expensive, delicate, and fragile components that can be easilydamager or destroyed, even with the use of expensive specialized tools,equipment, fixtures, and facilities.

SUMMARY

Exemplary embodiments provide a redundant interwoven TFT array for anLCD device where the odd horizontal conductors are driven by a firstgate driver while the even horizontal conductors are driven by a secondgate driver. Further, the odd vertical conductors are driven by a firstsource driver while the even vertical conductors are driven by a secondsource driver. Separate DIB and power supplies may be used for the firstand second set of gate/source drivers. If a failure were to occur, oneset of source/gate drivers may be turned off, causing only every otherline of pixels to cease operation, while the remaining pixels continueto operate. When the redundant interwoven TFT array is manufactured at ahigh density, the loss of every other line of pixels may not benoticeable to the observer. Any loss in luminance due to the failure ofevery other line of pixels can be accounted for by increasing thebacklight power/luminance.

In another embodiment, each horizontal and vertical conductor may be inelectrical contact with a first and second control system. Initially,the entire display is driven by the first control system. When/if afailure occurs in the first control system, it is powered down and thesecond control system maintains operation of the entire display.

An exemplary TFT array and LCD thus continues to produce images evenafter a failure of a gate/source driver, DIB, power supply, orconductor. If the TFT array is applied densely enough, the failure willnot be noticeable to an observer.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 provides a side elevational view of a traditional liquid crystaldisplay device.

FIG. 2 illustrates a simplified and enlarged elevational view of atraditional TFT array if viewed from the perspective of an intendedobserver.

FIG. 3 illustrates a simplified and enlarged view of an embodiment ofthe interwoven redundant TFT array if viewed from the perspective of anintended observer.

FIG. 4 provides a logical flow chart for an exemplary method forcontrolling the luminance of the display based on backlight power aftera failure of a gate/source driver, power supply, or conductor.

FIG. 5 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer.

FIG. 6 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer.

FIG. 7 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer.

FIG. 8 provides a logical flow chart for an exemplary method forcontrolling the redundant TFT array system shown in FIG. 7.

FIG. 9 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer.

FIG. 10 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer.

DETAILED DESCRIPTION

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which exemplary embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, the size and relative sizes of layers and regions may beexaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on” another element or layer, the element or layer can bedirectly on another element or layer or intervening elements or layers.In contrast, when an element is referred to as being “directly on”another element or layer, there are no intervening elements or layerspresent. Like numbers refer to like elements throughout. As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “lower”, “upper” and the like, may beused herein for ease of description to describe the relationship of oneelement or feature to another element(s) or feature(s) as illustrated inthe figures. It will be understood that the spatially relative terms areintended to encompass different orientations of the device in use oroperation, in addition to the orientation depicted in the figures. Forexample, if the device in the figures is turned over, elements describedas “lower” relative to other elements or features would then be oriented“upper” relative the other elements or features. Thus, the exemplaryterm “lower” can encompass both an orientation of above and below. Thedevice may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used hereininterpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Embodiments of the invention are described herein with reference toillustrations that are schematic illustrations of idealized embodiments(and intermediate structures) of the invention. As such, variations fromthe shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, are to be expected. Thus,embodiments of the invention should not be construed as limited to theparticular shapes of regions illustrated herein but are to includedeviations in shapes that result, for example, from manufacturing.

For example, an implanted region illustrated as a rectangle will,typically, have rounded or curved features and/or a gradient of implantconcentration at its edges rather than a binary change from implanted tonon-implanted region. Likewise, a buried region formed by implantationmay result in some implantation in the region between the buried regionand the surface through which the implantation takes place. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the actual shape of a region of adevice and are not intended to limit the scope of the invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Much of the detail for constructing a flat panel liquid crystal display(LCD) 10, as shown in side sectional view in FIG. 1, is known in the artand is unaffected by the exemplary embodiments, so that detail is notrepeated here. For purposes of this application, the relevant details ofthe exemplary embodiments are typically located between the front andrear plates 12, 14 of the liquid crystal display 10. Both front plate 12and rear plate 14 are visually transparent. Both are typicallyconstructed of glass and provide the conventional rigidity. In theapplicable art, front plate 12 is generally referred to as the “colorfilter” (CF) plate, and rear plate 14 is generally referred to as the“thin film transistor” (TFT) plate. According to known principles of therelevant art, a layer of liquid crystal material is contained in a thincavity 16 maintained between the plates 12, 14 by a sealing adhesive 18that extends around a periphery of the plates.

By known principles, electrical interaction of the respective plates 12,14 with the liquid crystal material causes localized alignment of theliquid crystal material in cavity 16. This alignment affects thetransmissibility of the backlight 27 through the plates 12, 14 at thatlocalized point. A display area visible through an external face 20 ofthe LCD 10 is effectively divided into a large plurality of pixels orcolor groups. In one known arrangement, the pixels or color groups arefurther divided into red, green and blue sub-pixels. The close proximityof the sub-pixels allows them to co-act to provide a visual perceptionof a single pixel in one of literally thousands of color variations thatcan be achieved through combinations of intensity of the aforementionedthree colors. Of course, other designs are possible which may use red,green, blue, and yellow sub-pixels and these would be within the scopeof the exemplary embodiments. Further, some arrangements may use two ofthe same color sub-pixels, such as red, green, first blue, and secondblue sub-pixels, and this would also be within the scope of theexemplary embodiments. Any number, color, and pairings of sub-pixelswould be within the scope of the exemplary embodiments. Further, anytype of backlight 27 may be used with the exemplary embodiments,including but not limited to edge-lit, direct-lit, or a hybrid type ofdesign. Embodiments could also be used with LCD's that are not back-litand instead rely on reflected ambient light to create an image.

The intensity variations of each sub-pixel are achieved through theselective alignment and non-alignment of the liquid crystal materialimmediately adjacent to the sub-pixels. Specifically, the TFT array 25,when activated, act upon the liquid crystal material to change thepolarization plane of the liquid crystal material. The interaction ofthe liquid crystal material with the front polarizer 55 and rearpolarizer 50 alters the emission intensity of each sub-pixel to createthe overall color of light emitted by the color group or pixel.

FIG. 2 illustrates a simplified and enlarged view of traditional TFTarray 25 if viewed from the perspective of an intended observer. Aplurality of horizontal conductors 37 are arranged with a plurality ofvertical conductors 36 to create a plurality of sub-pixels 49. As knownin the art, a transistor 39 is preferably placed within each sub-pixel49. A gate driver 41 is in electrical communication with a displayinterface board (DIB) 47 and is used to control the horizontalconductors 37. A source driver 46 is also in electrical communicationwith the DIB 47 and is used to control the vertical conductors 36. Apower supply 40 may provide power through the DIB 47 to the gate driver41 and source driver 46. Each sub-pixel 49 in the assembly can becontrolled when the gate driver 41 activates the appropriate horizontalconductor 37 while the source driver 46 activates the correspondingvertical conductor 36.

As FIG. 2 illustrates, the TFT array of 25 requires the operation ofsource driver 46, gate driver 41, DIB 47, and power supply 40 to orientthe sub-pixels 49 and create and image. If any of these devices were tofail, then the entire LCD would fail to create an image. This issometimes referred to as a ‘single point failure.’ As discussed above,the failure of the entire LCD is undesirable but has traditionally beena significant risk for LCD displays.

FIG. 3 illustrates a simplified and enlarged view of an exemplaryembodiment of the TFT array if viewed from the perspective of anintended observer. Herein the terms ‘odd’ and ‘even’ will be used todescribe alternating conductors where the numerical counting begins inthe upper left hand corner of the TFT array. The terms ‘odd’ and ‘even’are simply used to denote the alternating pattern, and do not requireany specific number of conductors or counting scheme. Further, the terms‘horizontal’ and ‘vertical’ will be used to describe the conductors butthese do not require the specific orientation as it is known that LCD'smay be rotated 90 degrees. In other words, the gate drivers herein maybe used to control vertical conductors and the source drivers may beused to control horizontal conductors or vice versa.

In this embodiment a first gate driver 135 is used to control the oddhorizontal conductors 160 while a second gate driver 137 is used tocontrol the even horizontal conductors 166. Similarly, a first sourcedriver 136 is used to control the odd vertical conductors 164 while asecond source driver 138 is used to control the even vertical conductors162. A first DIB 126 is in electrical communication with the first gatedriver 135 and first source driver 136. A first power supply 125provides power through the DIB 126 and to the first gate and sourcedrivers 135 and 136. A second DIB 128 is in electrical communicationwith the second gate driver 137 and second source driver 138. A secondpower supply 127 provides power through the DIB 128 and to the secondgate and source drivers 137 and 138.

During normal operations, both sets of conductors 160/164 and 162/166and their associated components would operate simultaneously. In atleast one embodiment, both sets of conductors and their associatedcomponents would be generating the same image. If the horizontalconductors 160, vertical conductors 164, first gate driver 135, firstsource driver 136, DIB 126, or power supply 125 were to fail, thesecomponents (known herein as the first TFT assembly 900) would be turnedoff or powered down. Conversely, if the horizontal conductors 166,vertical conductors 162, second gate driver 137, second source driver138, DIB 128, or power supply 127 were to fail, these components (knownherein as the second TFT assembly 950) would be turned off or powereddown. If the first TFT assembly 900 were turned off, the second TFTassembly 950 may continue to create the image on the LCD. Conversely, ifthe second TFT assembly 950 were turned off, the first TFT assembly 900may continue to create the image on the LCD.

The intersection of conductors 160, 164, 162, and 166 create a pluralityof sub-pixels 149, each of which preferably contains a transistor 139.Depending on the resolution of the TFT array (i.e. how densely are theconductors laid out) and the specific application for the LCD (i.e. whatis being shown graphically) the loss of every other conductor may not benoticeable to the observer. It has been found that modern manufacturingtechniques allow the resolution of the TFT array to be constructedsufficiently high so that a loss of every other line is not noticeableto the observer. For example, high resolution TFT arrays (over 300pixels per inch (ppi)) may lose every other conductor line which wouldresult in about half the resolution (approximately 150 ppi) and despitethe application; this may not be noticeable to the user. In mediumresolution displays (approximately 150 ppi), this may be slightlynoticeable to the observer, depending on the application of the LCD.While it is estimated that the human eye may only be able to perceiveresolutions up to 300 ppi, modern manufacturing techniques have shownthat TFT arrays can be constructed as high as 325 ppi and very possiblyhigher. Thus, while the human eye may not perceive the full resolutionof an exemplary TFT array in full operation, a failure in any of thesource/gate drivers, power supplies, or conductors may not result in anynoticeable loss of resolution to the observer.

It has been found that while the change in resolution may not benoticeable to the observer, the display luminance may drop noticeablywhen either the first 900 or second 950 TFT assembly is turned off. Toaccount for this phenomenon, an exemplary system may detect when afailure has occurred and may increase the backlight to account for thechange in display luminance. This process is illustrated in FIG. 4.

In some embodiments, the DIB 126 and DIB 128 contain built-in-test (BIT)circuitry, which may detect a failure in one of the TFT assemblycomponents and cause the TFT assembly containing the failure to beturned off. In some embodiments, a graphics processor 800 may be placedin electrical communication with the DIB 126 and DIB 128. The graphicsprocessor 800 may contain BIT circuitry, either instead of or inaddition to the BIT circuitry found in DIB 126 and DIB 128. To determineif there is a failure within a source or gate driver, the BIT circuitrymay monitor the ripple carry outputs of the source and gate drivers andreport a failure upstream, possibly to the graphics processor 800, whichmay then turn off the TFT assembly containing the failure. In otherembodiments, the failure may not be detected by BIT circuitry and may bedetected by the observer who can manually select an optionalreversionary button 870 to turn off the failed TFT assembly. Thereversionary button 870 may also accept input from the observer, so asto cycle through several modes including but not limited to: both firstand second TFT assemblies 900 and 950 (1× backlight), only first TFTassembly 900 (2× backlight), only second TFT assembly 950 (2×backlight).

In some techniques, the backlight is controlled using a power feedbackloop, where the power to the backlight is controlled based onmeasurements of current and/or power and these measurements aremonitored by a feedback loop. For these techniques, the desired power isroughly doubled when the system or observer detects a failure and one ofthe TFT assemblies is turned off. This embodiment is illustrated in FIG.4, which provides a logical flowchart that can be executed by many typesof software drivers or microprocessors. In some embodiments, the logicillustrated in FIG. 4 may be operated by the graphics processor 800.

In other techniques, the backlight may be controlled using a luminancefeedback loop, where the luminance within the backlight cavity iscontrolled based on luminance measurements from a light sensor placedwithin the cavity and monitored through an electrical feedback loop. Forthese techniques, the desired luminance may be roughly doubled when thesystem detects a failure and turns off the TFT assembly containing thefailure.

Unlike traditional digital binary logic buffers which can be tri-statedto selectively allow a single output from multiple tri-state bufferedoutput signals to interface to a single electrical wire or trace, LCDsource drivers are analog based which are traditionally not capable ofbeing tri-stated. Furthermore, even in a powered down state,back-driving a source/gate driver could result in permanent damage tothe powered-down source/gate driver or improper operation of the LCD.The preferred embodiment is to incorporate a logic switch or circuit onthe TFT matrix which effectively electrically isolates the twosource/gate drivers. A second embodiment is to incorporate this logicswitch or circuit in the source/gate drive IC.

FIG. 5 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer. In this embodiment, control block 1 is controllingevery even horizontal row of subpixels through horizontal conductors315. As used herein, every even horizontal row of subpixels isconsidered to be the 2^(nd) line, 4^(th) line, etc. Control block 2 iscontrolling every odd horizontal row of subpixels through horizontalconductors 320. As used herein, every odd horizontal row of subpixels isconsidered to be the 1^(st) line, 3^(rd) line, 5^(th) line, etc.

Control block 1 also has a plurality of vertical conductors 310 whichcontrol every odd horizontal row of subpixels. Control block 2 also hasa plurality of vertical conductors 305 which control every evenhorizontal row of subpixels. Also it should be noted that each of thehorizontal conductors 315 and 320 are positioned immediately below theodd rows of subpixels. Also, there are no horizontal conductors placedbelow the even rows of subpixels. Here, it can be observed that duringfull operation, both control blocks 1 and 2 are operating so that everysubpixel is active. If control block 2 were to fail, then only the oddrows of subpixels would be active. If control block 1 were to fail, thenonly the even rows of subpixels would be active. Because of theintersection 300, more than one source layer may be required.

FIG. 6 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer. In this embodiment, control block 1 is controllingevery odd horizontal row of subpixels through horizontal conductors 415.Control block 2 is controlling every even horizontal row of subpixelsthrough horizontal conductors 420. As used herein, every odd horizontalrow of subpixels is considered to be the 1^(st) line, 3^(rd) line,5^(th) line, etc.

Control block 1 also has a plurality of vertical conductors 410 whichcontrol every odd horizontal row of subpixels. Control block 2 also hasa plurality of vertical conductors 405 which control every evenhorizontal row of subpixels. Also it should be noted that each of thehorizontal conductors 415 and 420 are positioned immediately below theodd rows of subpixels. Also, there are no horizontal conductors placedbelow the even rows of subpixels. Here, it can be observed that duringfull operation, both control blocks 1 and 2 are operating so that everysubpixel is active. If control block 2 were to fail, then control block1 would power only half of the remaining subpixels. If control block 1were to fail, then control block 2 would power only half of theremaining subpixels. Because of the intersection 400, more than onesource layer may be required.

FIG. 7 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer. In this embodiment, gate 235 and source 236 areable to control every subpixel through horizontal conductors 200 andvertical conductors 210. Further, gate 237 and source 238 are also ableto control every subpixel through horizontal conductors 200 and verticalconductors 210. In this embodiment, if gate 235 or source 236 were tofail, all of the subpixels could still be controlled by gate 237 andsource 238. Alternatively, if gate 237 and source 238 were to fail, allof the subpixels could still be controlled by gate 235 or source 236.

In this embodiment, a first DIB 126 is in electrical communication withthe first gate driver 235 and first source driver 236. A first powersupply 125 provides power through the DIB 126 and to the first gate andsource drivers 235 and 236. A second DIB 128 is in electricalcommunication with the second gate driver 237 and second source driver238. A second power supply 127 provides power through the DIB 128 and tothe second gate and source drivers 237 and 238.

FIG. 8 provides a logical flow chart for an exemplary method forcontrolling the redundant TFT array system shown in FIG. 7. If the firstgate driver 235, first source driver 236, DIB 126, or power supply 125were to fail, these components (known herein as the first controlassembly 298) would be turned off or powered down. Conversely, if thesecond gate driver 237, second source driver 238, DIB 128, or powersupply 127 were to fail, these components (known herein as the secondcontrol assembly 299) would be turned off or powered down. If the firstcontrol assembly 298 were turned off, the second control assembly 299may continue to create the image on the LCD. Conversely, if the secondcontrol assembly 299 were turned off, the first control assembly 198 maycontinue to create the image on the LCD.

In some embodiments, the DIB 126 and DIB 128 contain built-in-test (BIT)circuitry, which may detect a failure in one of the TFT assemblycomponents and cause the TFT assembly containing the failure to beturned off. In some embodiments, a graphics processor 800 may be placedin electrical communication with the DIB 126 and DIB 128. The graphicsprocessor 800 may contain BIT circuitry, either instead of or inaddition to the BIT circuitry found in DIB 126 and DIB 128. To determineif there is a failure within a source or gate driver, the BIT circuitrymay monitor the ripple carry outputs of the source and gate drivers andreport a failure upstream, possibly to the graphics processor 800, whichmay then turn off the TFT assembly containing the failure. In otherembodiments, the failure may not be detected by BIT circuitry and may bedetected by the observer who can manually select an optionalreversionary button 870 to turn off the failed TFT assembly.

FIG. 9 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer. In this embodiment, control block 1 is split intotop-left source drivers 500 and top-right source drivers 400. Further,control block 2 is split into bottom-left source drivers 525 andbottom-right source drivers 526. The subpixels on the left hand side ofthe display can be controlled by the left-gate drivers 545 through thehorizontal conductors 555. The subpixels on the left hand side of thedisplay can also be controlled by either the top-left source drivers 500or the bottom-left source drivers 525 through the vertical conductors580. Similarly, the subpixels on the right hand side of the display canbe controlled by the right-gate drivers 540 through the horizontalconductors 550. The subpixels on the right hand side of the display canalso be controlled by either the top-right source drivers 400 or thebottom-right source drivers 526 through the vertical conductors 585.

Here, if the top-left source drivers 500 were to fail, the subpixels onthe left side of the display could still be controlled by thebottom-left source drivers 525, and vice versa. Further, if thetop-right source drivers 400 were to fail, the subpixels on the righthand side of the display could still be controlled by the bottom-rightsource drivers 526, and vice versa.

FIG. 10 illustrates a simplified and enlarged view of another embodimentof the interwoven redundant TFT array if viewed from the perspective ofan intended observer. Here, every odd horizontal row of subpixels iscontrolled by control block 1 through horizontal conductors 700.Further, every odd column of subpixels is controlled by control block 1through vertical conductors 710. Similarly, every even horizontal row ofsubpixels is controlled by control block 2 through horizontal conductors735. Finally, every even column of subpixels is controlled by controlblock 2 through vertical conductors 725.

In this embodiment, if control block 1 were to fail, control block 2could continue to drive 25% of the available subpixels. If control block2 were to fail, control block 1 could continue to drive 25% of theavailable subpixels.

Having shown and described preferred embodiments of the invention, thoseskilled in the art will realize that many variations and modificationsmay be made to affect the described embodiments and still be within thescope of the claimed invention. Additionally, many of the elementsindicated above may be altered or replaced by different elements whichwill provide the same result and fall within the spirit of the exemplaryembodiments.

We claim:
 1. A redundant control system for a liquid crystal display(LCD) comprising: a TFT array having horizontal and vertical conductionlines; a first source driver and a first gate driver which operate theTFT array; and a second source driver and a second gate driver instandby mode until a failure is detected within either the first sourcedriver or first gate driver.
 2. The redundant control system of claim 1further comprising: a first display interface board (DIB) in electricalcommunication with the first source driver and first gate driver and asecond DIB in electrical communication with the second source driver andsecond gate driver.
 3. The redundant control system of claim 2 furthercomprising: a first power supply in electrical communication with thefirst DIB; and a second power supply in electrical communication withthe second DIB.
 4. The redundant control system of claim 2 furthercomprising: a graphics processor in electrical communication with thefirst and second DIBs.
 5. The redundant control system of claim 4further comprising: a reversionary button in electrical communicationwith the graphics processor.
 6. The redundant control system of claim 5wherein: the reversionary button allows a user to switch between thefirst DIB and second DIB.
 7. The redundant control system of claim 2wherein: the first DIB is adapted to detect a failure in the firstsource driver or first gate driver.
 8. The redundant control system ofclaim 4 wherein: the graphics processor is adapted to detect a failurein the first source driver, first gate driver, or first DIB.
 9. A methodfor controlling a TFT array with an active first control assembly and adormant second control assembly, the method comprising the steps of:driving the TFT array with the first control assembly; detecting whethera failure has occurred within the first control assembly; driving theTFT array with the second control assembly if a failure is detected inthe first control assembly; and continuing to drive the TFT array withthe first control assembly if no failures are detected in the firstcontrol assembly.
 10. The method of claim 9 wherein: the first andsecond control systems each comprise a source driver, gate driver,display interface board (DIB), and power supply.
 11. The method of claim9 wherein: the step of detecting whether a failure has occurred withinthe first control assembly is performed by a graphics processor inelectrical communication with the first control assembly.
 12. The methodof claim 9 wherein: the step of detecting whether a failure has occurredwithin the first control assembly is performed by a display interfaceboard (DIB) which forms a part of the first control system.
 13. Themethod of claim 9 further comprising the step of: accepting input from areversionary button which permits a user to switch between the first andsecond control systems.
 14. A redundant control system for a TFT arraycomprising: a plurality of horizontal conduction lines; a first gatedriver in electrical contact with each horizontal conduction line; asecond gate driver in electrical contact with each horizontal conductionline; a plurality of vertical conduction lines; a first source driver inelectrical contact with each vertical conduction line; a second sourcedriver in electrical contact with each vertical conduction line; a firstdisplay interface board (DIB) in electrical contact with the first gatedriver and first source driver; and a second display interface board(DIB) in electrical contact with the second gate driver and secondsource driver; wherein the second gate driver, second source driver, andsecond DIB remain dormant until a failure is detected in the first gatedriver, first source driver, and first DIB.
 15. The redundant controlsystem of claim 14 further comprising: a reversionary button adapted topermit a user to select between the first gate driver, first sourcedriver, and first DIB or the second gate driver, second source driver,and second DIB.
 16. The redundant control system of claim 14 furthercomprising: a first power supply in electrical communication with thefirst DIB; and a second power supply in electrical communication withthe second DIB.
 17. The redundant control system of claim 14 furthercomprising: a graphics processor adapted to sense a failure in the firstgate driver, first source driver, or first DIB and if so, switch thecontrol of the TFT array to the second gate driver, second sourcedriver, and second DIB.
 18. The redundant control system of claim 14further comprising: a graphics processor in electrical contact with thefirst and second DIBs; and a reversionary button in electrical contactwith the graphics processor.
 19. The redundant control system of claim18 wherein: the reversionary button accepts input from a user whichdirects the graphics processor to switch between the first gate driver,first source driver, and first DIB or the second gate driver, secondsource driver, and second DIB.